In vivo studies of periodontal wound healing have demonstrated the potential of cells derived from the periodontal ligament to regenerate a functional connective tissue attachment consisting of dental cementum, periodontal ligament and alveolar bone. However, we have little understanding of the factors which regulate the proliferation, migration and differentiation of this cell population during this remarkable example of wound healing due in part to the difficulty in designing in vivo studies to dissect the complex series of events which occur during periodontal regeneration. Since homogenous cultures of cementoblasts or periodontal ligament fibroblasts have not yet been described, we have adopted an alternate strategy to study periodontal regeneration; identify extracellular matrix proteins specific to periodontal tissues. Our preliminary studies, as well as those of others, suggest that type XII collagen is present in periodontal ligament extracellular matrix but not in alveolar bone, cementum, dentin or gingival connective tissue and may, therefore, serve as a marker of periodontal ligament gene expression. We have raised polyclonal antibodies to a 30 kDa pepsin-solubilized fragment of mammalian type XII collagen and have used this preparation to screen a periodontal ligament cDNA library for cDNAs encoding this domain. It is our hypothesis that factors present in the periodontal wound healing environment play a central role in the regulation of periodontal regeneration. The intent of this application is to use both polyclonal antibodies and cDNAs to type XII collagen to assess type XII collagen as a marker of periodontal ligament extracellular matrix and, in conjunction with periodontal ligament cell cultures which express type XII collagen, develop an in vitro model of periodontal regeneration. Both soluble and matrix associated factors present in the periodontal wound healing environment will then be studied for their effects on the in vitro expression of type XII collagen.